Vulnerability · CVE-2026-27171
zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition.
Published Feb 18, 2026 · catalog updated Feb 18, 2026 · zlib before 1.3.2 allows
Last checked Nov 12, 2026. A connected source was read within the last 7 days.
Check if you run it
No confirmed exploitation is on record for CVE-2026-27171. EPSS is 0.25%. Act only if a listed version of zlib before 1.3.2 allows is installed.
Gaps on this record
- The stored product name is a package slug. The name on this page is taken from the title (zlib before 1.3.2 allows).
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
Same product and reporting
- CVE-2026-27820 · Critical
- CVE-2023-45853 · Critical
- CVE-2022-37434 · Critical
- CVE-2016-9843 · Critical
- Severity
- Low2.9
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 0.25%
- Remediation
- Version ranges on file
- Affected products
- vendor zlib zlib 0 <1.3.2
zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition.
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- vendor zlib zlib 0 <1.3.20 <1.3.2
How to fix CVE-2026-27171
Upgrade
CVE-2026-27171 lists a fix boundary at 1.3.2. Compare the installed build with that boundary before you change production.
Version check
Seen in 0 <1.3.2
Advisory
Open the cve_org record and follow its fix.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
No confirmed exploitation is on record for CVE-2026-27171. EPSS is 0.25%. Act only if a listed version of zlib before 1.3.2 allows is installed.
Which versions are affected?
Compare what you have installed with zlib zlib 0 <1.3.2 0 <1.3.2. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
No weakness class is stored. EPSS 0.25%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Feb 18, 2026 · EUVD
Detected
zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition.
Feb 18, 2026 · EUVD
Updated
zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition.
Sources
- CVE.orgVulnerability recordCVE-2026-27171
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-27171
30-day exploitation probability 0.25%
first.org - EUVDVulnerability recordEUVD-2026-8063
zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition.
euvd.enisa.europa.eu
References
Freshness
Last verified in this catalog Nov 12, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.
- FIRST EPSSNov 9, 2026
- CVE.orgNov 9, 2026
- EUVDNov 9, 2026